Related to KEVLAR-and-SPECTRA-like materials

[autoset 0]

Hello everybody, i'm an amateur skydiver who wants to learn everything possible about this awesome sport.

I have done my research even before taking my first jump, and if i'm not wrong entire rigs and canopies are made from these materials Kevlar or Spectra which are the strongest textile materials ever made (they make bodyarmour equipment with this)

I have read these materials weak points are exposure to high/very low temperatures, humidity and exposure to UV light, I have also read Kevlar can lose up to 50% of its strength in just a few months if not properly protected from light (UV light being the one who damages it the most)

Now here's the question, does the Kevlar continue to be the strongest textile material of all (even Nylon) after it has lost as much as 50% of its strength? I suppose its still the strongest after the strength lose, if not, i dont think they would use it to continue manufacturing rigs.

[IanHarrop 37]

These are not the only materials used.

This page has a link to the manual for riggers titled FAA Handbook 8083-17.
It has tons of information about the various materials and what they are used for in skydiving.

http://www.parachutemanuals.com/Other/

"Where troubles melt like lemon drops, away above the chimney tops, that's where you'll find me" Dorothy

[riggerrob 558]

You are partially correct.
Nylon is still the dominant material for sheet fabrics (i.e. canopies and containers), and nylon is still the preferred narrow fabric (webbings and tapes) for harnesses.
Nylon is still the best material for harnesses because it stretches a little during hard openings.

Dacron suspension lines were fashionable on the first generation of square (ram-air) parachutes, but skydivers whined about how bulky it was.
Since the early 1980s, skydivers have experimented with a variety of non-stretch materials, including aramids.
Kevlar (an aramid) was the first non-stretch material that we experimented. Kevlar's greatest advantage is its light-weight, low-bulk and zero-stretch. However, as you mentioned it is rather "fragile" and now is limited to reserve suspension lines and reinforcing tapes. A typical reserve only gets deployed once or twice during its 20 year service life.

The next "miracle fiber" was Spectra (the name was coined by the patent-holder: Allied Signal) (Performance Designs calls it 'micro line") - a polyethylene similar to that used in grocery bags. Spectra has most of the advantages of Kevlar with fewer disadvantages. The primary disadvantage of Spectra is that it shrinks (due to heat) out of trim after as little as 300 jumps. Spectra is by far the most widely used suspension line.

Since then, skydivers have tried a variety of advanced aramids including Vectran and several versions of High Modulus Aramids.

[JohnRich 4]

Quote

entire rigs and canopies are made from these materials Kevlar or Spectra which are the strongest textile materials ever made

I believe that neither rigs nor parachutes are made with kevlar. There are a few parachutes that use kevlar lines.

There is much more involved in the selection of parachute fabric than just strength. The textile engineers have a term called "modulus" which refers to how stretchable a fabric is. Kevlar doesn't stretch much at all, compared to nylon or dacron. That stretchiness helps absorb the opening shock by spreading out the force, and then returns to normal dimensions. Since kevlar doesn't stretch, the force is transmitted directly to the seams and joints, putting higher loads on those portions of the parachute. And the skydiver feels more opening shock also.

Furthermore, if you try to create a hybrid using both kevlar and nylon, then you have difficulties trying to integrate the two properties together. For example, if kevlar and nylon are sewn together, since one stretches and the other doesn't, then you get busted stitches.

Even the military with all their research money, haven't come up with a good way yet to overcome all of the difficulties of making ejection chutes out of kevlar.

Use the search function here with the word "kevlar", wade through all the crap, and you'll turn up past discussions on this issue.

[cobaltdan 0]

btw: the patent holder of ultrahigh molecular weight polyethylene is DSM in the netherlands where the fiber is produced under the trade name dyneema. honeywell (allied signal) licensed the technology from dsm for production in the u.s. and produces fiber under the name spectra.

and whereas spectra can shrink and go out of trim after as little as 300 jumps, this really only happens on canopies that open very quickly. most modern canopies with soft openings using spectra will remain in usable trim for 600-1000 jumps.

-

Daniel Preston <><>
atairaerodynamics.com (sport)
atairaerospace.com (military)